'Treasure trove of marine life' discovered

The vast, dark deep-seas surrounding Antarctica are teeming with hundreds of species unknown to science, according to a new study.

The diverse sponges, some of which are carnivorous, free-swimming worms, sea cucumbers, crustaceans, and molluscs living in the Weddell Sea will provide new insights into the evolution of ocean life

Among them are 674 new species of isopod, an order of crustaceans, 585 of them new to science, revealing much more diversity than expected in this cold and largely unstudied place, challenging the common assumption that deep sea diversity is depressed in high latitudes or polar areas, even though it is known that the inhabitants of the Southern Ocean continental shelf are very slow-growing compared with those that bask in tropical waters

Lead author of the paper in Nature was Prof Angelika Brandt from the Zoological Institute and Zoological Museum, University Hamburg.

She said: "The Antarctic deep sea is potentially the cradle of life of the global marine species. Our research results challenge suggestions that the deep sea diversity in the Southern Ocean is poor.

"We now have a better understanding in the evolution of the marine species and how they can adapt to changes in climate and environments."

Among the wonders of the deep are single-celled creatures that aggregate in branching structures measuring a couple of millimetres across, called Komokiacea, sea cucumbers measuring up to eight inches in length, many molluscs, three quarters of which are unknown outside the region, and predatory sponges that eat little crustaceans called copepods. The latter "are really nasty, though small in size," Prof Brandt told The Daily Telegraph.

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The scientists describe how creatures in the deeper parts of the Southern Ocean - the source for much of the deep water in the world ocean - are likely to be related to animals living in both the adjacent shallower waters and in other parts of the deep ocean.

A key question for scientists is whether shallow water species colonised the deep ocean or vice versa. The research findings suggest the glacial cycle of advance and retreat of ice led to an intermingling of species that originated in shallow and deep water habitats.

The origins depends on the organism investigated, with some isopods originating from the deep, while others are former inhabitants of the ancient polar supercontinent Gondwana that have since invaded the ocean.

Dr Katrin Linse, marine biologist from British Antarctic Survey, near Cambridge, says, "What was once thought to be a featureless abyss is in fact a dynamic, variable and biologically rich environment. Finding this extraordinary treasure trove of marine life is our first step to understanding the complex relationships between the deep ocean and distribution of marine life."

Three research expeditions, as part of the ANDEEP project (Antarctic benthic deep-sea biodiversity), organised by Prof Brandt onboard the German research ship Polarstern, took place between 2002 and 2005. During this time, and the following analysis, an international team from 14 research organisations investigated the seafloor landscape, its continental slope rise and changing water depths to build a remarkable picture of life in this little known region of the ocean.

They found over 700 new species at depths of 774 - 6348 metres. If the ice sheet retreats as a result of climate change, Prof Brandt said that the water mass migrating to the Antarctic bottom will decrease. Because this is flow is a "motor" that can transport species and food into the deep sea, it could harm the life that thrives there, she warned.

Scientists from from the German Centre for Marine Biodiversity, British Antarctic Survey National Oceanographic Centre, Southampton, and Scottish Association for Marine Science were involved in the analyses of the species and sediments.